COEXTRUDED HEAT SEALING COMPOSITE POLYOLEFIN FILM

摘要

TITLE: COEXTRUDED HEAT SEALING COMPOSITE POLYOLEFIN FILMInventor: BORIS W. PETRONABSTRACT OF THE DISCLOSUREA composite film of a coextruded high density ethylenepolymer resin and a film forming hot-melt adhesive. The filmis readily sealable in a conventional forming and fillingmachine such as used in the manufacture of potato chips. Theprocess of making the film comprises coextruding a high densityethylene polymer resin and a film forming hot-melt adhesivewhich is highly viscous, and cooling thereafter. The filmforming hot melt adhesive may be a mixture of ethylene vinylacetate copolymer, wax, and tackifier . The temperature ofextrusion is about the same for both components of the film.Preferably, a tubular coextrudate is formed and inflated withair to desired size and then air cooled so that the compositehas time to solidify without blocking at the nip. The collapsingof the tube is effected when the laminate is still warm to hot,in order to prevent creases.